Fine grain developers



and thioureas.

their action-to the dissolving of the silver halidev Patented May 15, 1945 UNITED STATES PATENT oFFicE FINE GRAIN DEVELOPERS Richard W. Bonn and John I. Crabtree, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey I No Drawing. Application December 29, 1941, Serial No. 424,808

Claims. (on. 95-88) This invention relates to addition agents for photographic developers.

A number of compounds have been found which, when added to a developer of moderate or low activity, decrease the graininess produced by that solution. These are mostly solvents for silver halide and include thiocyanates, thiosulfates The common theory attributes unstable in the alkaline developing solutions and, on standing, especially following aeration, decompose to sodium sulfide which not only produces a high fog but'also stains or scums on the surface of films.

It is, therefore, an object of the present invention to provide novel addition agents for photographic developers. A further object is to provide addition agent 'for photographic developers which will produce a reduction in graininess of the image. A still further object is to provide addition agents for photographic developers which will produce a reduction in graininess without a great loss in emulsion speed. A further object is to provide addition agents for developers which will produce a reduction in graininess without the production of high fog. Another object is to provide more stable addition agents which will not decompose when the developer solution is stored or aerated. Other objects will appear from the following description of our invention. I These objects are accomplished by incorporating in a photographic developer a quaternary nitrogen salt of a benzothiazole, especially aquaternary nitrogen salt of an aminobenzothiazole.

During the course of these investigations, the properties of these addition agents have been checked by a number of different methods of exposure; development, and measurement of graininess. Most of the quantitative data were gathered by exposing films carrying a gelatino-silver halide emulsion behind a gray step wedge and developing strips of these for different periods in a special developing machine, using high agitation to produce uniform results. The emulsion speed was usually determined by the minimum useful gradient method, which was checked by threshold and inertia speeds. Graininess was preferably determined by matched enlargements from negatives of equal printing contrast but this method was supplemented by direct microscopic comparison at 20 diameters.

A comparison of graininess was made by assigning numbers to degrees of graininess differing by equal gralniness increments as judged visually. By assigning a graininess value to a high speed photographic emulsion developed in a standard developer, the relative graininess values could then be recorded for the same emulsion developed in the same developer with theaddition of the various agents used according to our invention.

These addition agents were tested in a number of different formulas but, inaddition, all were tested in the following basic developer formula for izitercomparison:

The addition agents'were either dissolved directly in the developer or added from stock solutions.

The following compounds were found to be effective for use in photographic developers:

-aminobenzothiazole-metho-p-toluene sulfonate 2-amino-6-methylbonzothiazole-metho p-toluene aulionate 2 s mo 2-amino6-methyl benzothlazole-etho-otoluene sulionate I Z-aminMl-methyl benzothiazole, ethoethyl sulionnte 8 E30 \C NHa sHaOH Z-aminc-G-methyl benzothlazoie. fl-hydroxyetho bromide SOs-OCrHg 2-hydrazino benzothiazole-methn-p-tolueno sulfonate s CH 0-memyl-2-benzothiazoyl glycin-metho-p-toluene sulfonnte N e g s 00-0111 these agents are substituted in the "6" position, they are preferably prepared by direct thiccyanogenation oi the corresponding amine (see Kaufmann, Berichte 673; 944-48, 193%). The

glycin is formed by the reaction "of the amine Example 2 lvionomethyl p-aminophenof.

sulfate "gram 5.0 Sodium sulfite (anhydrous) do Sodium metaborate do Potassium bromide do.. 1.0

2 amino-B-methyl benzothiazole-metho= -toluene sulfonate "grams" 0.5 Water to "liter-.. 1.0

This solution, developing in about 25 minutes at 68 F., gives a greater graininess reduction than that produced by the ordinary p-phenyl enediamine developers and is free of staining properties.

Example 2 Monomethyl p-aminophenol- I sulfate "grams" 1.0

Hydroquinone do 4.0

Sodium sulfite (anhydrous) do 15.0

Sodium carbonate (anhydrous) do- 22.5 40 Potassium bromide do 1.1

2 amino-G-methyl benzothiazoie, ethoethyi sulionate "grams" 0.15

Adipamide-bis (2-benzothiazole-metho-p-toiuene sulfonote) urea or from the 2-ch10r0benz0thiaz0le. When 75 Water to liter Water "liter" 1.0

C s 050cm Thi s formula possesses a remarkably short de- C Y velopment time for a flne grain developer yield- -CNH-N=C f ll; mg a gamma, of about 1.0 in 5 minutes at 68 F. CHZCH on a high speed rollfilm. N

I Example 3 vC a SOaQ-Cfh w v N-(ethyl- 3 -methyl- 4 -amm0phenyl )gly- M th l-seoondnry butyl-ketone-2-benzothiaz0yl clneamide ydrazone-metho-p-toluene-sulionaic V 2-amino-6-methyl benzothiazole metho S S 0H, cm.

c'-NHN=( :-cmcHz-o=N- NH- J/ N\ i Q N v 0Q, SCI-OCH: on, so cm Diaoetonyl-di (2-benzothiazoyl-ketone)di (metho-p-ialuene sulfonate) The amino-benzothiazoles may be. prepared p-toluene suifonate' grams- 0.2 by-the methods commonly described in the liter- Sodium sulfite (anhydrous) do 100.0 ature, for example from the correspon i th Sodium metaborate do 20.0

- graininess of the ima e,

The chemicals are dissolved in the order given in hot water (about 160 F.). This solution requires 30 to 60 minutes development time, depending onthe emulsion and degree agitation at 68 F. It gives especially large reductions in graininess with only moderate losses in emul-' sion speed, and especially low fog.

Example 4 N- (ethyl 3 methyl 4 aminophenyl glycineamide grams 5.0

2-amino-6-.methyl benzothiazole metho p-toluene sulionate rams 0.2 Sodium sulflte (anhydrous) ..do 50.0 p-Hydroxy-phenyl-glycin do- 5.0 4 Sodium metaborate do- 10.0 Water to "liter" 1.0

The chemicals are dissolved in the order given in hot water (about 160'F.).This solution requires to 30 minutes developmenttime at 68 Examples but has glycineamide developer used in this formula is described-pin Dickey and McNally U. S. application Serial No. 301,446, filed 'October 26, 1939).

In addition to thei-r property or reducing the we have found that F. It gives slightly less graininess reduction than;

the advantages oi shorter time of development and also gives low log. (The many oi the addition agents used according to our invention decrease the fog produced. For example, with 2-aminobenzothiazole nietho-ptoluene sulfonate the netfog isfonly /2 or less that obtained without the addition of the agents used according to our invention. Similarly, with adipamide-bis-(2-benzothiazole metho p-toluene sulfonate) an appreciable reduction in fog is noted.

The following table illustrates the relative values oi graininess, emulsion speed. an fog obtained by using the compounds ot'our invention in the basic Elon developer iormula given above. These values are for a high speed panchromatic roll iilm.

Grains Emul- Addition sion 1P5 speed 9 z-aminobenzothiuole-metho-p- 5 62 2-8 tolnenesulionate 3g g: g a-amino -6 methyl -benzothiuolo-otho-ethyl suliate.l.--.- 0. 5- 52 28-24 0. Adi do-bis (fl-benzothia- & 7 65 0. dnetho-p-toluene sulio- IM) 30 19 0. Non 1m Empirical scale based on eqnalvisual mama.

a sea as:

ylenedia'mine was although a cold tone may be produced. A glossy, sometimes whitish, surface is also a common characteristic.

, In addition to the ordinary Elon or Elon-hydroquinone, developers, other developing agents may be used with the addition agents of our invention. Elon was found to be as sensitive to additionagents as any 01 the conventionaIdevelopers. Developing agents requiring a high pH such as hydroquinone were ineiileient. -p-Phenvery sensitive tothe addition agents -oi our inventionv when used in weakly alkaline solutions. Certain p-phenylenediamine derivatives were found to be even more sensitive, and to produce lower graininess when the agents of. our invention were'added to them.

These agents may not only be used in solutions employing only one developing agent but also in solutions employing two or more developing agents such as Elon and hydroquinone; paraphenylenediamine or its derivatives and 'a phydroxyphenyl glycin; or paraphenylenediamine, p-hydroxyphenyl glycin, and Elon.

In addition to the use of quaternary salts of benzothiazoles, the quaternary salts of structural- 1y analogous heterocyclics may be used: for .ex- 'ample,the sulfur atom of the benzothiazole rin may be replaced by an etmllene group as in the quinoline ring or by an imino group as in the benzimidazole ring.

It will be understood that the formulas included hereinare illustrative only and thatour invention is to be taken as limited only by the scope of the appended claims.

- We claim:

1. #A fine-grain photographic developer comprising a,d'eveloping agent and a quaternary nitrog'en salt of .a Z-aminobenzothiazole.

2. A flne-grain, photographic developer comprising-a developing agent and a 2-aminobenzothiazqle alkyl-p-toluenesulfonate.

3. I fine-grain photographic developer comprising a developing agent and a z-aminobenzothiazole metho-p-toluene sulfonate.

4. A fine-grain photographic developer comprising a developing agent and 2-amino-6-methyl-benzothiazole-metho-p-toluene sulfonate.

5.1 fine-grain photographic developer comprising a developing agent and 2-amino-6-methyl benzothiazole, etho-ethyl sulionate.

momma w. 11mm. JOHN'I. 

